Fuse link



E. F. Bco'rHE Aug. 10, 1937.

FUSE LINK Filed April 22, 1935 INVENTOR.

EUGENE F. BOOTHE.

ATTORNEY.

Patented t Aug. 10, 1937 UNITED STATES FUSE LINK Eugene F. Boothe, St. Louis, Mo., assignor to James R. Kearney Corporation, St. Louis, Mo., la corporation of Missouri AppucauonApril z2, 1935, serial Nt. 17,632

8 Claims.

In the protection of electrical equipment fuse links are enclosedin casings known as cartridges, numerous forms of which are in common use. The present invention relates to a fuse link of the expulsion type adapted` for use in such cartridges. f

One `object of my invention is to provide a fuse link which will not only be electrically eilicient but will be of superior mechanical construction imparting desirable rigidity to the device.

Another object of my invention is to so construct the link that it may be applied to various ,types of cartridges in commpn use whether such.

cartridges were designed for tension or expulsion links.

Still another object of my invention is lto provide a fuse link which will embody in its structure such features as will enable it to function as an eiective protective device when connected directly ina circuit without the use of a cartridge of any kind.

In the accompanying drawing which illustrates a fuse link made in accordance with my invention, Figure 1 is a longitudinal section through one form of. cartridge to which my fuse link may be applied and is shown therein; Figure 2 is an enlarged sectional View of the fuse link; Figure 3 is a top plan View of the link; Figure 4 is a longitudinal section of the upper end of another form of cartridge; and Figure 5 is a sectional view of the link after the fuse is blown, such View also showing the alteration of the link to adapt -it for use in the form of cartridge shown in Figure 4.

, Referring rst to Figure 1, in which one form of cartridge is shown for purposes of illustration only, the numeral 6 is a. tube of ber or other insulating material. Secured to the upper end of the tube 6 is a metal contact block 'l provided with the usual latch ring 8 and having its upper end closed by a threaded cap 9. Surrounding the tube Ii is a protective porcelain sleeve IB below which is a metal contact block Il, preferably removably secured to tube S by a set-screw I2. This block is provided with a lug i3 threaded to receive a thumb-screw I4 for securing one terminal of the fuse which passes|through a vertical opening I 5 in the lug.

50 The upper end of the fuse link is formed of three parts, an attached button head comprising a cylindrical portion I 6 and a disc il, a detachable button head comprising a tubular part I8 and a ange i9, and a ilat terminal 20 provided with a notch 2l. 'I'he lower end of terminal 20 is reduced and enters a tube 22 of liber or other insulating material. Contained within the tube 22 is a fusible section which, in the form shown, comprises a pair of wires 23 and 2t secured together by a fusible joint 25. The wire 23 is connected to the terminal 2U and wire 2li to a stranded cable 26 forming the other terminal of the link. This latt'er terminal is adapted to pass down through the tube ii and be connected to Contact block in by thumb-screw er. Enter- 10 ing the lower end of the insulating tube 22 is a thin metal tube 2l provided at its lower end with a flange 2t. This tube is secured to the ilexible conductor 26 by any suitable means such as solder 29 andvis surrounded by a coil spring 30 com- :l5 pressed between the lower end of the tube 22 and the ange 28. The solder 2d may be used to at,- tach a small disc 3| on which the rating of the fuse maybe marked.

In using my'fuse link in connection with a 20 cartridge such as shown in Figure l, the exible conductor is dropped down through the tube E, the tubular member I8 entering the bore, and the flange I9 oi the removable button head resting upon theupper end of the contact block l where 25 it is secured by screw-cap 9. The lower end of the exible conductor or terminal 26 is now secured by screw I4. 1 It need not, however, be drawn taut as is necessary in the case of a link using a tension spring, but may be allowed to hang 30 loosely as shown. -f

In case a cartridge is used having a smaller opening than the tubular part IB of the removable button headfthis head is slipped down over the link, the cylindrical part I6 of the iixed head 35 entering Ithe bore of the tube and thefdisc II bearing on the upper end of the block.

In Figure i l2 have shown a form of cartridge in which the contact block 'I' is provided with a vertical face against which a. at terminal is 40 adapted to be clamped by the head o a screw 32. To adapt my link for use in such a cartridge, not only is the large butto-n head removed but the small button head is cut on, producing a terminal such as shown in Figure 5 which may be 45 readily secured in position as shown, the body oi the screw 32 entering notch 2i in the terminal.

In the use Yof my iuse link, when an overload occurs the fusible joint 25 will be melted and wires 23 and 2li will be separated by the expansion of spring 3U. Rapid and wide separation of the conductors to prevent arcing is secured, as due to the light construction there is but little inertia to be overcome by the spring. As the expansive action of the spring is wholly indem' 55 `pendent of the cartridge, the link may be connected directly' in the line to be protected to secure the same results as when enclosed in a cartridge. 5 Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A fuse link comprising a tubular member, a fusible section lying in said tubular member and having a connection extending from one end of the tubular member, an electrical conductor Secured to the fusible section and extending out of the other end of the tubular member, an abut-v ment on the conductor, a coil expansion spring 15 surrounding the conductor and having one end engaging the abutment and the other end engaging the tubular member, and rigid means extending the length of the coil spring for supporting said spring.

aY fusible section lying in said tubular4 member and having a connection extending from one end of the tubular member, an electrical conductor secured to the other end of the fusible section and extending out of the other end of the tubular member, an abutment on a portion ofthe conductor exterior of the tubular member, a sleeve surrounding the conductor and having one telescoping with the tubular member, and a coil expansion spring surrounding the sleeve and interposed between the abutment and the adjacent end of the tubular member.

3. An expulsion fuse comprising a tubular casing closed yat the top and open at the bottom,

a fusible section in said casing and connected.'

to the top thereof, an electrical conductor connected to the fusible section and extending to the exterior of the casing atits open end, a tu-v member, a second tubular member surroundingi the terminal and secured thereto, and an expan- 2. A fuse link comprising a tubular member,'

end engaging the abutment and the other end sion spring surrounding said second named tubular member andA operating'thereon when the fusible section 'is melted to separate the ltubular members. I

5. A fuse link comprising a tubular member of insulating material, a fusible section in said tubular member, a rigid terminal at one end of the tubular member, a flexible terminal at the other end thereof, a second tubular member surrounding the' flexible terminal and secured thereto. and an expansion spring surrounding said second named tubular member and operating thereon when the fusible section is melted to separate the tubular members.

6. A fuse link comprising a tubular member of insulating material, a fusible section in said tubular member, a rigid terminal at one end of the tubular member, a flexible terminal at the other end thereof, a second tubular member surrounding the flexible terminal and secured thereto, said l second named tubular member entering the first named tubular member and being provided with an abutment, and an expansion spring surroundingvagainst the rst named tubular member and the abutment.

7. A fuse link comprising a tubular member of insulating material, a fusible section in said tubular member, a flexible terminal at one end of said tubular member, a fiat rigidterminal at the other. end of said tubular member, a fixed head on said terminal, said fixed head comprising a cylindrical portion and a projecting disc, and a removable head, said removable head comprising a tubular part surrounding the cylindrical portion of the rst named head and having a projecting flange. y

8. A unitary fuse link structure adapted to be positioned in a fuse cartridge, said link structure comprising a tubular element, a conducting element carried by the upper end of said tubular element for engagement with a terminal, conducting means extending from the other end of said tubular element and of suilicient length to extend out of the fuse cartridge for connection to a second terminal, a fusible element electrically connecting said conducting means and said first mentioned conducting element, and resilient means strainedbetween the tubular elementv and the conducting means and acting on the upper means after rupture of -the fusible element.

EUGENE F. BOOI'HE.` 

